I was going through the documentation of Cisco Packet Tracer when I read about the Modem Dial-up Utility. This utility was available on the Desktop tab of both PCs and Laptops.

The documentation said a PC/Laptop, Cloud and a router were required. It also mentioned that the router should have a user name authentication (username WORD password LINE) in addition to a modem interface.

The modem interface of the cloud must also have valid a phone number. But I didn’t know how to go about it. So googled for a long time and found this slideshare presentation. Starting from slide 17 it had the information I needed.

So I ended up writing this article on creating a Cisco Packet Tracer Dial Up dial up lab.Continue Reading…

EIGRP (Enhanced Interior Gateway Routing Protocol) is a Cisco proprietary routing protocol which even though seems to work like a Distance-Vector protocol is in fact several notches above other routing protocols in the distance-vector domain. While configuring it is a breeze what happens behind the scenes ? What goes in the wire when a “network” router subcommand is issued ? How do things converge quickly when a topology change occurs ? These questions made me create a simple topology in GNS3 and capture packets using wireshark. So join me in unraveling the mystery inside an EIGRP packet.Continue Reading…

Cisco has created a very good demo exam which resembles the real simulation used in the CCNP TSHOOT exam. While the trouble tickets asked in the demo are nowhere near the real TSHOOT exam it gives an idea of what kind of tickets to expect in the exam. This article is a walkthrough on how I answered the 4 tickets in the CCNP TSHOOT demo. The 4 tickets in the demo jumble up each time the demo is opened so the order of tickets I mention in this article will be different compared to the one you’ll encounter in the demo. All tickets contain the same issue of the client not being able to ping the webserver so you can differentiate each ticket based on the output of tracert.

Connecting GNS3 to the internet is just another step to bring your emulated network lab closer to real gear. There are many ways to do this based on what internet connection you are using. If you just have an ADSL modem/router connected to the ethernet port of your physical machine having a private IP address it is very simple to get your lab to the internet. But if you are using a WiFi connection/Data card/a device that requires you to assign a public IP on the physical interface getting your lab to access the internet requires a few more commands in Linux or a few more clicks in Windows. Apart from making configuration changes to your operating system NAT has to be configured on the emulated router that connects to the internet.Continue Reading…

PPP or Point-to-Point Protocol is a type of Layer 2 protocol (Data-link layer) used mainly for WAN. PPP features two methods of authentication PAP (Password Authentication Protocol) and CHAP (Challenge Handshake Authentication Protocol) a c0nnection is established between two peers only after authentication succeeds. PAP sends the password in cleartext for authentication so CHAP is preferred and will be discussed in this article. PPP encapsulation is possible only over a serial link. This article will showcase two different topologies first with two routers and second with three routers.Continue Reading…

Even if you forget your Cisco device (read router or switch) password you can recover it by following the steps outlined in this article. This includes enable passwords, secret passwords, telnet, SSH and console passwords. This process involves changing the configuration register of your Cisco device so that it ignores the NVRAM contents and loads the default configuration. For this process you have to get into the ROM monitor mode so you need to have serial console access to the Cisco switch/router.Continue Reading…